Method and apparatus for cleaning grease filters in a ventilating system

ABSTRACT

A grease extractor is mounted in a ventilation system for commercial cooking units. Control means are provided to alternately cycle spray nozzles located both above and below the filter to direct water and detergent mixed with water to the top and bottom of the filter in alternating sequences. Baffles are installed internal to the ventilating system to prevent the spray water from reaching the cooking unit and to direct the air flow through the filters. Troughs at the end of the baffles divert the spent water into a drain.

United States Patent [1 1 [111 3,805,685 Carns 1 Apr. 23, 1974 [5 METHODAND APPARATUS FOR 3,329,529 7/1967 Lamar 134 99 CLEANING GREASE FILTERSIN A 2,633,929 4/1953 Farr 55/242 X 3,055,285 9/1962 Gaylord 98/115 KVENTILATING SYSTEM 3,140,828 7/1964 Galanor 134/109 [75] Inventor:Vernon J. Carns, Modesto, Calif. 3,324,867 6/1967 Freese l34/99 z I 9 Il s I [73] Assignee glasfilflel Industries, nc Modesto Primary Exammerwmlam F. 013% Assistant Examiner-Paul Devinsky [22] Filed: Jan. 15, 1973Attorney, Agent, or FirmWarren F. B. Lindsley [21] Appl. No.: 323,778

[57] ABSTRACT [52] U.S. Cl 98/115 K, 134/57 R, 134/95, A greaseextractor is mounted in a ventilation system 134/29, 134/36, 134/199 forcommercial cooking units. Control means are pro- 51 Int. Cl F23j 11/00,B08b 3/08 vided to alternately Cycle p y nozzles located both 53 Fie|d fSearch 9 115 K, 115 55 22 above and below the filter to direct water anddeter- 55/233 242 DIG 36; 137/ 24 13; 134/57 R gent mixed with water tothe top and bottom of the 58 R, 99, 95, 199, 115 R, 171, 40, 36, 34,filter in alternating sequences. Baffles are installed in- 29 26 ternalto the ventilating system to prevent the spray water from reaching thecooking unit and to direct the 5 Ref Ci d air flow through the filters.Troughs at the end of the UNITED STATES PATENTS baffles divert the spentwater into a drain.

3,242,652 3/1966 Malenchini 55/242 10 Claims, 7 Drawing Figures m m nAPR23 1914 3.805685 SHEEI 1 BF 3 FIE-E17 Fi 20 36 METHOD AND APPARATUS FORCLEANING GREASE FILTERS IN A VENTILATING SYSTEM BACKGROUND OF THEINVENTION This invention relates generally to a ventilating unit greaseextractor adapted to extract grease and steamladen vapors from thevicinity of cooking ranges and the like, and more particularly to animproved method and apparatus for cleaning the grease extractor.

FIELD OF THE INVENTION In most large cooking units, especially those inrestaurants and other commercial establishments, a forced airventilating system with grease filters or extractors is used for theremoval of the odors, vapors and heat created during cooking. Suchvapors are normally laden with vaporized fat, greases and oils liberatedduring the cooking processes. The grease filters along with bafflesPRIOR ART The removal of the grease filters for the cleaning process isa dirty, messy job and frequently is postponed as long as possible. Ifthe filters are not cleaned, the can become clogged with the grease anddirt trapped by the filter. Thus the filter itself, if it is not removedand cleaned often, frequently becomes a fire hazard.

Cleaning apparatus such as a spray nozzle mounted above the filter wasprovided to accomplish the cleaning of the filter while installed in theventilating system. Baffles and a drain were provided to prevent thecleaning spray mixture from contacting the cooking unit and to drain offthe dirty water after the cleaning process. However, most of the dirt isembedded in the grease laden filters from beneath the filter and is forthe most part untouched by the spray nozzle directed at the filter fromabove. Also, for best cleaning results an agitated action is necessary.Thus what is needed is a method and apparatus for thoroughly cleaningthe grease filter of a ventilating system of a cooking unit.

SUMMARY OF THE INVENTION The ventilating system for a cooking unitaccording to the present invention comprises separate ventilatingsections mounted over the cooking unit and connected to a common airchamber which is in turn connected to a plenum and flue exhausting to achimney. An exhaust fan or blower induces an air flow from above thecooking unit into each ventilating section, the air chamber and into theflue and chimney. Each ventilating section includes a grease filter orextractor mounted in the air flow, an upper and lower liquid sprayingmeans such as nozzles directly to the top and bottom respectively of thegrease filter, baffles mounted in the air chamber to direct the air flowand to prevent the liquid from the spray nozzles from reaching thecooking unit, troughs to divert the sprayed liquid into a drain, andassociated plumbing to carry cleaning liquid to the upper and lowerspray nozzles. Associated plumbing and control means are provided toalternately cycle the liquid through the upper and lower spray nozzles.Temperature sensitive means may be located in each air chamber toactuate one or both spray nozzles and turn on the exhaust ventilatingsystem and shut off the system supplying air to the kitchen in the eventof a fire.

The method of cleaning the grease filters comprises the steps ofprewashing the grease filters by alternately spraying liquid at thegrease filter under a high pressure through the upper spray nozzle andthen the lower spray nozzle, warming the filters with hot liquid toapproximately the temperature of the liquid .by alternately cycling theupper and lower spray nozzles, adding degreasing chemicals to the hotliquid for spraying the grease filter via the upper spray nozzles,shutting off the liquid and the degreasing chemicals to the spraynozzles, allowing the liquid water mixture to soak into the greasefilter, and finally rinsing the grease filter by alternately cycling hotliquid to the upper and lower grease nozzles at a high pressure to cleanoff any grease from the filters by alternately spraying the liquid ontothe grease filter from above and below the filter.

It is, therefore, an object of the present invention to provide anenhanced ventilating system for use in cooperation with commercialcooking units.

It is another object of the present invention to provide a ventilatingsystem having an enhanced apparatus for cleaning a grease filter in aventilating system without removing the grease filter from theventilating unit.

It is yet another object to provide apparatus for cleaning greasefilters in a ventilating system by alternately applying a cleaning fluidto the grease filter from 'above and below the grease filter.

BRIEF DESCRIPTION OF THE DRAWING The various novel features of thisinvention, along with the foregoing and other objects, as well as theinvention itself both as to its organization and method of operation,may be more fully understood from the following description of anillustrated embodiment when read in conjunction with the accompanyingdrawing, wherein:

FIG. 1 is a perspective view of a typical commercial cooking unitprovided with a ventilating system including improved grease filtersaccording to the present invention;

FIG. 2 is a vertical cross section of a ventilating section taken alongline 2-2 of FIG. 1 showing the grease filter and associated apparatusaccording to the present invention which may be used above deep-fatfrying units;

FIG. 3 is a vertical cross section of a ventilating section taken alongline 3-3 of FIG. 1 showing the grease filter and associated apparatusfor use above surface cooking units;

FIG. 4 is a vertical cross section of a ventilating section taken alongline 4-4 of FIG. 1 showing the grease filter and associated apparatusaccording to the present invention for use above a broiler and/or ovenunit;

FIG. 5 is a cross-sectional view of a ventilating system showing asecond embodiment of the present invention;

FIG. 6 is a diagrammatic view of the interconnect liquid control supplyfor use with the ventilating system of FIG. 1; and

FIG. 7 is a simplified schematic of a control unit for cycling theapparatus according to the present inven-' tion through a washing cycleof the grease filter.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, FIG. 1illustrates a typical commercial cooking unit l0vcomprising two deep-fatfrying units 12, a grill unit 14, a two-range unit 16, and a broilerunit 18, together with appropriate ovens associated with the broilerunit 18. The selection and the arrangement of the particular units isgenerally a matter of choice and can be varied at will without affectingthe operation of the present invention. The placement of the units suchas the two deep-fat frying units 12 and the grill and surface units areto provide an arrangement dictated by the use of the unit and theparticular type of hood associated with that commercial cooking unit.

The cooking unit 10, as shown in FIG. 1, is provided with a ventilatingsystem 22 having a plurality of ventilating sections 24, 26 and 28. Thefirst ventilating section 24 uses a low profile hood or canopy 30 whichoverhangs the deep-fat frying units 12. A cross section of theventilating section used over the deep-fat frying units 12 is shown inFIG. 2. A shallower hood 32 and different baffles comprise the secondventilating section usedover the surface and grill units 16 and 14. Thehood 32 over these units is also a low profile hood and a cross sectionof the ventilating section 26 for the surface cooking unit 16 and grillunit 14 is shown in FIG. 3. .The third ventilating section 28, the ovenor broiler ventilating section, is a high'profile system adapted to bearranged above higher level units such as the broiler unit 18 and ovenunits 20 stacked as shown in FIG. 1. The air input 34 and bafflearrangement in the oven ventilating section 28 for the broiler and ovenunits is shown in FIG. 4. The height of each of the ventilating sectionsis such that the separate entrance ways are as close as possible to thesurface of the cooking unit while at the same time allowing sufficientclearance for the necessary operation of the cooking unit.

Referring again to FIG. 1, all three ventilating sections 24, 26 and 28are connected to a common air type driven by an electrical motor can beused as the exhaust fan in the present embodiment. I

The function of the ventilating system 22 is to collect the fumes, smokeand grease-laden vapors coming from I the cooking unit 10 and to exhaustthe smoke and fumes to the atmosphere. This is accomplished as mentionedabove by maintaining a constant flow of air from the kitchen across thecooking unit 10 and out through the ventilating sections 24, 26 snd 28,the plenum 38 and the flue. The three ventilating sections are adaptedto rest on and be supported by the separate cooking units by means ofbrackets as shown in FIG. 1, and to fit closely around the sides andback of the cooking unit to direct the air flow from across the cookingunits 10 into the ventilating system 22. Optionally, the back of theventilating system 22 can include a separate duct work 40 opening intothe common air chamber 36 from the rear of the cooking units. This ductwork 40 can be used to direct flue gases from the cooking units into theventilating system 22 and out into the atmosphere. An adjustable draftregulator (not shown) can be provided in each section to adjust the airflow through each ventilating section.

In order to show the apparatus according to the present invention,reference is made to the cross-sectional views illustrating the air flowthrough the different sections as shown inFIGS. 2, 3 and 4 takentogether with FIG. 1.

Referring to FIGS. land 2, the deep-fat frying ventilating section 24comprises the elongated hood 30 extending over the deep-fat frying units12. The hot vapors from the deep-fat frying units 12 are drawn into anentrance way 42 at the rear of the hood 30 from the negative pressurecreated by the exhaust fan. The hot vapors are deflected rearwardly anddownwardly by an entrance baffle 44 over an upwardly and forwardlyextending bottom baffle 46. Theentrance baffle 44 froms an integral partof the rear of the hood 30 and inclines the hot vapors downwardly towardthe bottom baffle 46 and backward toward a rear wall 48. Internal to theI ventilating section is an upper spray forming means and chamber 36(internal to the units, see FIGS. 2, 3 and 4) which in turn is'connected'to a plenum 38. The plenum may-be connected by normalduct work eitherdirectly to the atmosphere outside of the kitchen or can be connected toa chimney or a flue in a conventional manner. An exhaust fan or blower(not shown) is provided in the plenum at some convenient location forthe purpose of inducing an air flow from the area above the cookingsurface through the ventilating sections 24, 26 and 28, the common airchamber 36 and the plenum 38 out into the atmosphere. It is obvious thatany type of fan such as the commonly known squirrel cage a lower sprayforming means such as the upper spray nozzle 50 and the lower spraynozzle 52. Both spray nozzles 50 and 52 are directed toward a greasefilter 54 mounted in the airstream. The entrance baffle 44 is formed atits lower section to operate as a lip to direct the liquid forced fromthe spray nozzles behind the bottom baffle 46 and on into a trough 56and drain pipe 58 combination. The grease is removed from the vapors bythe grease filter 54 and the remaining air passes into the plenum 38above the filter 54 via the common air chamber 36. r

The ventilating system according to the present invention is designed towash either grease filters or grease extractors in their normal positionin the ventilator section. The spray nozzles are located both above andbelow the grease filter and spray the cleaning liquid such as water anddetergent on the filter alternately from both top and bottom. The liquiddraining from the grease filters is collected in a trough with a drainpipe taking the spent liquid to a sewer. The function of a grease filteris to provide ample surface area to cool the vapors from the cookingunits sufficiently for the grease to be condensed and deposited on thefilter media. The efficiency is directly related to the clean surfacearea contacted by the grease-laden vapors. The grease filter may beconstructed of several sandwiched layers of deep corrugated steel meshbetween two expanded metal faces, held together by a steel channelframe. Drain holes are provided in the frame. The steel mesh may beconstructed of galvanized or stainless steel to prevent rust. It is thevery efficiency of the steel mesh which causes the problems of prior artcleaning units. The pulsating, alternating spray from both sides of thefilter according to the present invention permits a thorough cleaningthrough the multiple meshes of the filter.

Grease extractors may be used in the ventilating sections in place ofgrease filters. The grease extractors are generally centrifugalextractors which pass the greaseladen vapors through tortuous passagesat high velocities to sling off the grease from the extractor bycentrifugal force. Most of the grease drains into the trough, but someremains in the extractor. The extractors must also be cleanedperiodically to maintain their efficiency.

Still referring to FIGS. 1 and 2, the hood 30 and the entrance way 42extend along the length of the ventilating section 24 and thus extendalong the width of the two deep-fat frying units 12. Likewise theentrance baffle 44, the bottom baffle 46, the rear wall 48, and thegrease filter 54 extend across the width of the deep-fat fryingventilating section 24. The trough 56 formed at the bottom of theventilating section 24 can be downwardly sloped from one end to theother with the drain at the low section or can be downwardly sloped fromboth ends toward a centrally placed drain. The trough 56 extendsbasically beneath the filter 54 and baffles 44 and 46 to catch the watersprayed onto the filter 54 and any excess grease dripping from thefilter 54. The drain pipe 58 extends from the bottom of the trough 56and when the cleaning apparatus is in use, this drain pipe is connectedto a suitable sewer connection.

The grease filter 54 is mounted at an angle sloping downwardly towardthe front of the ventilating section 24 in order to provide a largersurface area to the vapors passing through the filter and also toprovide an angle for the cleaning fluids ejected by the spray nozzles 50and 52 to drip by gravity from the back and raised portion of the filter54 to the front lowered portion, through the drain holes in the filter54, along the inward portion of the entrance baffle 44, down across thelip of the entrance baffle 44 onto the internal portion of the bottombaffle 46 and into the trough 56 and drain pipe 58. The entrance baffle44 and the bottom baffle 46 are preferably fastened by clips or screws(not shown) for easy removal. Likewise the grease filter 54 ispressure-fit into place for easy removal.

The ventilating section 26 over the surface unit section as shown inFIG. 3 is similar in construction to the deepfat frying ventilatingsection 24 just described in FIG. 2. Because of the shorter hood 32required above the surface unit to provide for working area for thecook, the ventilating section 26 shown in FIG. 3 requires that thegrease filter be placed at a more severe angle. Referring to FIGS. 1 and3, the hot grease-laden vapors are gathered by the hood 32, directedthrough an entrance way 60 via an entrance baffle 62. The entrancebaffle 62, as shown by the arrows showing the air flow. is directeddownwardly and rearwardly toward a bottom baffle 64 and a rear wall 66.The hot vapors are drawn through another grease filter 65 or extractorlocated in the surface unit ventilating section 24 into the common airchamber 36 and out into the plenum 38. This ventilating section 24 alsoincludes a lower spraying apparatus and an upper spraying apparatusshown as a lower spray nozzle 68 directing a liquid spray to theunderside of the grease filter 65 and an upper spray nozzle 70 directinga liquid spray to the top section of the grease filter 65. Thisventilating section 24 is similarly formed such that the liquid sprayedonto the filter 65 by the upper and lower spray nozzles 68 and 70 isdirected via the interior portion of the entrance baffle 62 along a lipof the entrance baffle 62 down into a trough section 72 and from thetrough section 72 into a drain pipe 74. Again in this section, theentrance baffle 62 and bottom baffles 64 are fastened by screws or clipsfor easy removal along with the grease filter 65.

A third ventilating section, the broiler and oven ventilating section28, is shown in cross-sectional view in FIG. 4. Referring to FIGS. 1 and4, the grill and oven ventilating section 28 comprises similar apparatusas that shown and described in FIGS. 2 and 3 for the deepfat frying andsurface units. The grill and oven ventilating section 28, however, is ahigh-level unit and thus the grease filter is located in a differentplane. ln FIG. 4 the hot vapors from the grill and oven cooking units 18and 20 are directed via the air input 34 directly into the ventilatingsection 28 without an extending hood. The air input 34 is formed fromsheet metal formed inwardly and downwardly from the top of theventilating section 28. A lower lip of the air input 34 is formed fromsheet metal from the lower section of the ventilating system. The lowerlip is formed upwardly and outwardly from the bottom portion of theventilating section 28. Thus the entrance way 34 into the ventilatingsection 28 is at a sloping angle as shown in FIG. 4. A decorative screencan be used to cover the entrance way 34.

The broiler and oven ventilating section 28 is formed as a unitsupported directly by the broiler and oven unit. The ovenventilatingsection 28 is thus formed with a bottom section 78 for resting on thetop of the grill and oven units and an internally placed sheet metalbaffle 80 forming the internal air chamber 36. The hot vapors drawn fromthe front opening of the broiler and oven units are directed into theentrance way 34 across the entrance baffle 82 formed to reduce the crosssection of the exhaust stream to increase the air velocity. Fumes, whichmay contain grease, rising from the broiler or oven flues are divertedand directed by baffle 80 to the area between entrance way 34 andentrance baffle 82 at which place they are aspirated or induced into theexhaust stream entering grease filter 84. Grease filter 84 is supportedby brackets 86 for ease of removal in an upward and backward directionin the ventilating section 28. The grease vapors are removed by thegrease filter 84 and the remaining air is drawn into the common airchamber 36 shared with the other ventilating sections. In thisventilating section 28, an upper spraying device shown as a spray nozzle88 directs a liquid spray to the upward facing portion of the filter 84which in FIG. 4 is the section of the filter that meets the grease ladenvapor in the first incident. A lower spraying device, such as a lowerspray nozzle 90, is directed toward the under-portion of the greasefilter 84 which in this ventilating system is the rearward or clean airsection of the grease filter. The liquid sprayed by the spray nozzles 88and 90 is collected on the entrance bafile 82. The entrance baffle 82slopes slightly downward as the entrance baffle 82 extends toward therear of the ventilating section. The downward slope takes the spentcleaning liquid into a trough 92 at the rear of the ventilating sectionout into a drain pipe 94. The entrance baffle 82 prevents the spray fromthe nozzles 88 and 90 from escaping past the entrance way 34 out intothe broiler and oven units during a cleaning cycle.

The upper and lower spray nozzles of each ventilating section iscontrolled by a separate pair of remote control valves such as solenoidvalves interconnected with a main hot water valve and a detergent tank.Referring to FIG. 6, a schematic outline of the plumbinginterconnections isshown. A hot water input directs a cleaning liquidsuch as water via pipes 95 to a remote control valve Vrn controlling thepath of the water through a separate path or trough a venturi valve 96for siphoning a degreasing chemical such as detergent from a detergenttank 98. The water pipes 95 are directed to the three ventilatingsections, schematically shown as blocks 24, 26 and 28. The water pipes95 in each section are directed to an upper and lower remote controlvalve, schematically shown as VlB and VlT controlling the lower spraynozzles 52 and upper spray nozzle 50, respectively, of the deep-fatfrying ventilating section 24, V2B and V2T controlling the lower spraynozzle 68 and upper spray nozzle 70, respectively, of thesurfaceventilation section 26, and V3B and V3T controlling the lowerspray nozzle 90 and upper spray nozzle 88, respectively, of the oven andgrill ventilating section 28.

The normal wash is as follows: first, the pre-rinse hot water cycle isturned on, spraying water at a low pressure through the filters in thesection to be washed in an alternating manner, actuating first the topspray nozzle and then the bottom spray nozzle and repeating until thefilter is warmed by the hot water. After the pre-rinse cycle, a washcycle is performed. The detergent is siphoned into the water lines byclosing valve Vm, thereby forcing the water flow through the venturi.The venturi will siphon detergent from the detergent tank and add thedetergent to the hot water. It should be recognized that an electricpump may be used in place of or in addition to the venturi. The mixtureof water and detergent is directed to the same spray nozzles and themixture is again alternately sprayed on the filters from above and belowby alternately actuating the solenoid valves. After the wash cycle, asoak cycle permits the detergent and water mixture to soak in the filterfrom above and below to loosen any grease within the filter. After thesoak cycle, a high pressure hot water rinse is alternately directed tothe same upper and lower spray nozzles to blast off any grease with thealternating, pulsating water spray. After this 'cycle. the nextventilating section is cycled through the same wash cycle. A circuitcontrol means which may be used, for example, to control a wash cycle isshown in FIG. 7.

Referring to FIG. 7, the ventilation and washing of the grease filtercycles can be controlled manually by push buttons or automatically bytime switches. Depression of a FAN button 100 starts the ventilatingcycle by applying electrical power to the exhaust fan 101. The FAN light102 will be illuminated when the power is applied to the fan motor.Depressing the FAN button 100 activates relay R1, which through itscontacts both applies power to the exhaust fan 101 and provides aholding .circuit through normally closed contacts of both relays R2 andR3. In all relays, C represents the common or switching contact, NCrepresents the contact normally completed if the relay is not activated,and NO represents the contact completed with the C contact when therelay is activated.

Depressing the OFF button 104 opens all holding circuits whichde-energizes all relays, thereby stopping all power to all the devices.

A WASH button 106 is provided to manually start the wash cycles. Duringthe wash cycle the WASH light 108 is illuminated. Depressing the WASHbutton energizes relay R2. Energizing relay R2 stops the exhaust fan 101and energizes a timer 112 and contacts T1 for the PRE-RINSE cycle.Solenoid valves Vm and VlB are opened. Alternating relay 110 isactivated. Alternating relay 1 10 is an alternating means whichactivates and deactivates in a regular timed cycle to alternate theactivation of solenoid valves VlT and VlB. Valves VlB and VlTalternately activate the lower and upper valves 50 and 52 of ventilatingsection 24 (see H0. 6).

At the end of the PRE-RINSE cycle, timer 112 contacts T1 deactivatesenergizing contactsTZ for the WASH cycle. Valve Vm is closed, forcingthe water to flow through the venturi valve which siphons detergent intothe system. The higher pressure drop through the venturi leaves a lowerpressure for the spray nozzles and consequently a soft spray is appliedto the grease filters during a WASH cycle. The alternating relay 110again alternately activates the valves controlling the upper and lowerspray nozzles to cause the detergent and water mixture to be applied inalternating cycles to both sides of the filter.

It should also be recognized that it is intended to disclose and coverin this application the spraying of water and detergent mix on the topof the filters only and let this mixture soak in, thereby savingdetergent over alternating cycle usage.

At the end of the WASH cycle, contacts T3 of the timer 112 are energizedfor the SOAK cycle. Valve Vm is opened but both valves V18 and V1T areclosed, turning off the spray nozzles. The SOAK cycles allow thedetergent and water mixture to soak into the filters and loosen anyaccumulated grease in the filters.

When the SOAK cycle is completed, timer contacts T4 are energized forthe FINAL RINSE cycle. Valve VIB and VlT are alternately opened via thealternating relay 110. The high pressure hot water is pulsed,alternately through the upper and lower spray nozzles to the filter.After the FINAL RINSE cycle, assuming a multisection system, valves Vm,V113 and VlT are closed and the timer 112 is set to home. A step switch114 is energized to advance to the next position to permit control ofthe V28 and V2T valves in the ventilating section 26. The systemautomatically repeats the above cycle for the next section. Similarly,all of the ventilation sections are washed in turn via the step switch114 until all of the ventilation sections are cleaned.

At the conclusion of the FINAL RINSE cycle for the last section, relayR3 is tie-energized, stopping the cleaning cycle, resetting the stepswitch 114, resetting the timer 112 and closing all valves.

The control cycle for the wash cycle may be auto matic. A time switch-116 can be used to automatically start the wash or cleaning cycle duringthe time that the establishment is closed. No one need be around tostart the cycle.

Float switch 118 measures the level of the liquid detergent in thedetergent tank. If the level of detergent gets low, an indicating light120, marked LOW, is illuminated to notify an attendant that thedetergent supply needs replenishing.

Fire protection is automatically provided by thermostats F1, F2 and F3measuring the temperature of the gases rising from the cookingequipment. In case of abnormal temperature, the thermostats activate theexhaust blower (see FIG. 7) to draw the fire and smoke into theventilating system and also activate the water valves to spray water orfire preventative liquid through all of the upper and/or lower spraynozzles to prevent the flames from penetrating the grease filter. Theexhaust blower creates a negative pressure in the kitchen to helpprevent the fire and smoke from spreading to other areas. The system maybe arranged to shut off the fuel to the cooking unit in the event of afire by connecting the thermostats to a gas valve or electric powerswitch, thereby removing the fuel and heat supporting the fire. Thecircuit for controlling a fuel cut-off valve 122 is shown in FIG. 7.Whenever the temperature of the gases in any unit rises above theratings of the thermostats F1, F2 and F3, relay R4 is activated, openingall valves Vm, VlB, VlT and such, turning on the exhaust fan 101 andclosing the fuel cut-off valve 122.

Although the preferred embodiment discloses a ventilating systemdesigned to be mounted on the cooking units, it is obvious that theventilating section of the system could be designed for wall mounting orsuspended over the cooking units without departing from within the scopeof this invention. For instance, a ceiling suspended ventilating systemfor use over cooking units placed in the center of a room is shown inFIG. 5. in FIG. 5, two filter island type ventilating system 124 isshown. The island type ventilating system 124 comprises a hood 126supported from the ceiling by adjustable hangers 128. An air passage 130is provided to draw the hot grease-laden vapors past entrancebaffles132, bottom baffles 134 and through two grease filters 136 mounted withthe. tops of the grease filters 136 touching a common bracket 138 andwith the bottom of each grease filter 136 supported by the entrancebaffles 132. One lower nozzle 140 with a double head applies the sprayliquid to the bottom of the filters 136. Two upper nozzles 142, one foreach filter, apply the spray liquid to the top of the filter. Thecleaned air passes into a plenum 144 or flue chamber after the filters136. An exhaust fan (not shown) provides the negative air pressure todraw the air from around the cooking units used under the island typehood 126. The water from the filter is gathered by the bottom baffles134, directed to a trough 146 and a drain pipe 148. In this type ofapplication, the alternating cycle of the nozzles can activate both topnozzles 142 together and then the bottom nozzle 140.

Further, a control system is shown for cycling the wash cycle to operateon each ventilating section in turn. It is obvious that all ventilatingsections can be washed at one time by having one valve controlling alllower spray nozzles and another controlling all upper spray nozzles. Thesame alternating, pulsating wash cycle can be used, washing all of thefilters in the ventilating system at one time.

it is further obvious that other types of control systems could be usedwithout departing from the present invention. For instance, the timingcontrol and alternating relay could be obtained by using a standardwashing machine timer with a rinse alternating cycle. The timing of somecams activating the switches in a usual washing machine might have to bechanged but the intent is obvious.

The appended claims are, therefore, intended to cover and embrace anysuch modifications, within the limits only of the true spirit and scopeof the invention.

What is claimed is:

1. A ventilating system arranged above a cooking unit in close proximitythereto to remove vapors and gases emanating therefrom, said ventilatingsystem comprising:

a hood means placed above the cooking units for capturing the vapors andgases from the cooking units;

an air chamber connected to said hood means;

a plenum connecting said air chamber to the atmosphere;

a grease removing means placed in said air chamber for removing greasefrom the vapors and gases emanating from the cooking units, said greaseremoving meansbeing oriented in said air chamber to incline upward at anangle to the horizontal;

exhaust means associated with said plenum for inducing a current of airto draw the vapor and gases captured by said hook means through saidgrease removing means, said air chamber, and said plenum into theatmosphere;

an upper spray forming means mounted above said grease removing meansfor spraying a liquid against a top side of said grease removing means;

a lower spray forming means mounted below said grease removing means forspraying a liquid against a bottom side of said grease removing means;

control means for activating the upper and lower spray forming means forpermitting the liquid to be sprayed by the upper spray forming means andthe lower spray forming means onto the grease removing means;

a plurality of removable baffles fastened in said air chamber to directthe induced current of air through said grease removing means and toprevent the sprayed liquid from reaching the cooking units;

a trough formed in said air chamber to capture the spent sprayed liquid;and

a drain pipe connected to said trough for directing the sprayed liquidto a drain,

said control means includes remote control means and alternating meansto alternately activate the upper and lower spray forming means forpermitting the liquid to be alternately sprayed by the upper sprayforming means and the lower spray forming means.

2. A ventilating system as defined in claim 1 wherein the greaseremoving means is a noncorrosive steel grease filter comprising aplurality of sandwiched layers of deep-corrugated metal mesh, a pair ofexpanded metal faces, and a channel frame holding the mesh layersbetween the metal faces, said channel frame including a plurality ofdrain holes formed in at least one end of the channel frame.

3. A ventilating system as defined in claim 1 wherein the greaseremoving means is a noncorrosive steel, centrifugal grease extractor.

4. A ventilating system as defined in claim 1 wherein said upper andlower spray forming means each include a spray nozzle directed towardsaid grease removing means.

5. A ventilating system as defined in claim 1 wherein said remotecontrol means of said control means in cludes solenoid operated valvesalternately activated by said alternating means and alternatelycontrolling the liquid directed to said upper spray forming means andsaid lower spray forming means.

6. A ventilating system as defined in claim 5 wherein the liquid sprayedfrom said upper and lower spray forming means is water and a degreasingchemical such as detergent mixed with water and wherein the ventilatingsystem further includes means activated by said control means forintroducing the detergent to the water.

7. A ventilating system as defined in claim 6 further including timingmeans for controlling the operation of the solenoid operated valves, themeans for introducing the detergent to the water, and the alternatingmeans, to cycle the operation of each to allow water only and the waterand detergent mixture to be alternately and cyclically directed to bothsides of the grease removing means to clean the grease from the greaseremoving means.

8. A ventilating system as described in claim 1 further includingthermostats for controlling said control means to activate said exhaustfan and said upper and lower spray forming means to spray the greaseremoving means in the event of a fire in the ventilating system, andfurther including a means for interrupting the fuel flow to the cookingunit activated by said thermostat.

9. A ventilating system arranged above a cooking unit in close proximitythereto to remove vapor and gases emanating therefrom, said ventilatingsystem comprising:

a hood placed above the cooking units capturing the vapors and gasesfrom the cooking units;

an air chamber connected to said hood;

a plenum connecting said air chamber to the atmosphere;

a plurality of removable baffles fastened in said air chambers;

a grease filter removably fastened to said plurality of removablebaffles and oriented in said air cham-- bers to incline upward at anangle to the horizontal;

an exhaust fan mounted in' said plenum and inducing a current of air todraw the vapor and gases captured by said hood through said greasefilter, said air chamber, and said plenum into the atmosphere;

an upper spray nozzle mounted in said air chamber and directed to spraya liquid at the top side of said grease filter; I a lower spray nozzlemounted in said air chamber and directed to spray a liquid at the bottomside of said grease filter; plumbing means for connecting said upper andlower spray nozzles to a source of a liquid such as hot water; a tankcontaining detergent; valve means for introducing the detergent to thehot water via the plumbing means; solenoid operated valves connected tosaid plumbing means and controlling the flow of the hot water and thehot water and detergent mixture so said upper and lower spray nozzles;alternating means connected to said solenoid operated valves foralternately operating said solenoid operated valves; control means foractivating said alternating means, said valve means and said exhaust fanto operate the ventilating system and to cycle said alternating meansand 'said valve means to clean said grease fil ter; a trough formed insaid air chamber to capture the spent water; and a drain pipe-connectedto said trough for directing the spent water to a drain; a plurality ofremovable baffles formed to prevent the sprayed liquid from reaching thecooking units. 10. A process for cleaning grease from a grease filtermounted in a ventilating system at an inclined angle to the horizontal,the ventilating system being arranged above a cooking unit in closeproximity thereto and ineluding means for inducing a current of air tocarry grease-laden vapors from above the cooking units through thegrease filter, said process comprising:

prewashing the grease filter by alternately spraying at a high pressure,a hot liquid at the top side of the filter and then the bottom side ofthe filter, and then repeating until the grease filter is warmed to thetemperature of the hot liquid; adding a degreasing chemical to the hotliquid; washing the grease filters by alternately spraying at a lowerpressure, the mixture of the degreasing chemical and the hot liquid atthe top side of the filter and then the bottom side of the filter, andthen repeating until the grease filter is saturated by the mixture;allowing the mixture to soak into the grease filter and soften thegrease from the grease filter; and ringing the grease filter byalternately spraying at a high pressure, the hot liquid at the top sideof the filter and then the bottom side of the filter, and thenrepeating, thereby pulsing the hot liquid at the filter until themixture and the grease is removed from the filter.

1. A ventilating system arranged above a cooking unit in close proximitythereto to remove vapors and gases emanating therefrom, said ventilatingsystem comprising: a hood means placed above the cooking units forcapturing the vapors and gases from the cooking units; an air chamberconnected to said hood means; a plenum connecting said air chamber tothe atmosphere; a grease removing means placed in said air chamber forremoving grease from the vapors and gases emanating from the cookingunits, said grease removing means being oriented in said air chamber toincline upward at an angle to the horizontal; exhaust means associatedwith said plenum for inducing a current of air to draw the vapor andgases captured by said hook means through said grease removing means,said air chamber, and said plenum into the atmosphere; an upper sprayforming means mounted above said grease removing means for spraying aliquid against a top side of said grease removing means; a lower sprayforming means mounted below said grease removing means for spraying aliquid against a bottom side of said grease removing means; controlmeans for activating the upper and lower spray forming means forpermitting the liquid to be sprayed by the upper spray forming means andthe lower spray forming means onto the grease removing means; aplurality of removable baffles fastened in said air chamber to directthe induced current of air through said grease removing means and toprevent the sprayed liquid from reaching the cooking units; a troughformed in said air chamber to capture the spent sprayed liquid; and adrain pipe connected to said trough for directing the sprayed liquid toa drain, said control means includes remote control means andalternating means to alternately activate the upper and lower sprayforming means for permitting the liquid to be alternately sprayed by theupper spray forming means and the lower spray forming means.
 2. Aventilating system as defined in claim 1 wherein the grease removingmeans is a noncorrosive steel grease filter comprising a plurality ofsandwiched layers of deep-corrugated metal mesh, a pair of expandedmetal faces, and a channel frame holding the mesh layers between themetal faces, said channel frame including a plurality of drain holesformed in at least one end of the channel frame.
 3. A ventilating systemas defined in claim 1 wherein the grease removing means is anoncorrosive steel, centrifugal grease extractor.
 4. A ventilatingsystem as defined in claim 1 wherein said upper and lower spray formingmeans each include a spray nozzle directed toward said grease removingmeans.
 5. A ventilating system as defined in claim 1 wherein said remotecontrol means of said control means includes solenoid operated valvesalternately activated by said alternating means and alternatelycontrolling the liquid directed to said upper spray forming means andsaid lower spray forming means.
 6. A ventilating system as defined inclaim 5 wherein the liquid sprayed from said upper and lower sprayforming means is water and a degreasing chemical such as detergent mixedwith water and wherein the ventilatinG system further includes meansactivated by said control means for introducing the detergent to thewater.
 7. A ventilating system as defined in claim 6 further includingtiming means for controlling the operation of the solenoid operatedvalves, the means for introducing the detergent to the water, and thealternating means, to cycle the operation of each to allow water onlyand the water and detergent mixture to be alternately and cyclicallydirected to both sides of the grease removing means to clean the greasefrom the grease removing means.
 8. A ventilating system as described inclaim 1 further including thermostats for controlling said control meansto activate said exhaust fan and said upper and lower spray formingmeans to spray the grease removing means in the event of a fire in theventilating system, and further including a means for interrupting thefuel flow to the cooking unit activated by said thermostat.
 9. Aventilating system arranged above a cooking unit in close proximitythereto to remove vapor and gases emanating therefrom, said ventilatingsystem comprising: a hood placed above the cooking units capturing thevapors and gases from the cooking units; an air chamber connected tosaid hood; a plenum connecting said air chamber to the atmosphere; aplurality of removable baffles fastened in said air chambers; a greasefilter removably fastened to said plurality of removable baffles andoriented in said air chambers to incline upward at an angle to thehorizontal; an exhaust fan mounted in said plenum and inducing a currentof air to draw the vapor and gases captured by said hood through saidgrease filter, said air chamber, and said plenum into the atmosphere; anupper spray nozzle mounted in said air chamber and directed to spray aliquid at the top side of said grease filter; a lower spray nozzlemounted in said air chamber and directed to spray a liquid at the bottomside of said grease filter; plumbing means for connecting said upper andlower spray nozzles to a source of a liquid such as hot water; a tankcontaining detergent; valve means for introducing the detergent to thehot water via the plumbing means; solenoid operated valves connected tosaid plumbing means and controlling the flow of the hot water and thehot water and detergent mixture so said upper and lower spray nozzles;alternating means connected to said solenoid operated valves foralternately operating said solenoid operated valves; control means foractivating said alternating means, said valve means and said exhaust fanto operate the ventilating system and to cycle said alternating meansand said valve means to clean said grease filter; a trough formed insaid air chamber to capture the spent water; and a drain pipe-connectedto said trough for directing the spent water to a drain; a plurality ofremovable baffles formed to prevent the sprayed liquid from reaching thecooking units.
 10. A process for cleaning grease from a grease filtermounted in a ventilating system at an inclined angle to the horizontal,the ventilating system being arranged above a cooking unit in closeproximity thereto and including means for inducing a current of air tocarry grease-laden vapors from above the cooking units through thegrease filter, said process comprising: prewashing the grease filter byalternately spraying at a high pressure, a hot liquid at the top side ofthe filter and then the bottom side of the filter, and then repeatinguntil the grease filter is warmed to the temperature of the hot liquid;adding a degreasing chemical to the hot liquid; washing the greasefilters by alternately spraying at a lower pressure, the mixture of thedegreasing chemical and the hot liquid at the top side of the filter andthen the bottom side of the filter, and then repeating until the greasefilter is saturated by the mixture; allowing the mixture to soak intothe grease filter and softeN the grease from the grease filter; andringing the grease filter by alternately spraying at a high pressure,the hot liquid at the top side of the filter and then the bottom side ofthe filter, and then repeating, thereby pulsing the hot liquid at thefilter until the mixture and the grease is removed from the filter.